<!DOCTYPE html>  
<html>
<head>  
<meta charset="utf-8" />  
<title>HTML5之Canvas画圆形</title>  
  
</head>  
<body >  
   <canvas id="canvas" width="1200" height="560"/>  
   <script type="text/javascript">  
        var canvas=document.getElementById("canvas");  
        var context=canvas.getContext("2d");  
        context.fillStyle="red";  
        context.beginPath();  
        context.arc(600,300,200,0,Math.PI*2,true);  
        context.closePath();  
        context.fill();  
    </script>  
</body>  
</html>